Isochronous data transfers can be used by Universal Serial Bus (USB) devices designed to transfer data to or from a host at a constant rate. For example, systems that stream audio employ isochronous transfers for transmitting audio signals in real-time. Silicon Laboratories microcontrollers’ robust USB peripheral supports isochronous transfers, and each family’s assortment of additional high quality peripherals make them excellent single-chip solutions for USB-based embedded system designs.

This application note contains the following: a USB protocol overview concentrating on isochronous transfers; a firmware template that provides a starting point for custom USB Audio Class device firmware; and an example system illustrating requirements and operation of USB Audio Class devices.